Roundup is a non selective herbicide, so it will kill everything, including the KBG. That's why Morpheus uses a glove. That way he can target individual grass blades.

If the areas where you applied the RU are large, the KBG will take a long time to fill them in. Depending on the kind of RU you used, you may be able to seed a few days after applying it, but there are some flavors of RU that provide "extended protection" or something along those lines. If you used one of those, you won't be able to seed for quite a while. You'll need to check the label on the bottle you used.

This is not the best time to be reseeding in MA. If you seed now, you'll likely lose a fair amount to the heat of the summer, so you may need to seed again in the fall.

I'm trying to figure this out myself. I did as you did, though with a slightly different blend. I've never noticed Poa Annua before in my lawn, ever, and so I have always seen these discussions of Poa Annua as being a somewhat exotic problem.

So, my first thought when I first identified it this spring was to wonder whether my "sod quality" seeds were contaminated. I mean, I can't believe how much of this stuff showed up!

But on reflection I came to believe that the weed seeds (and, presumably, even the actual weed plants that I just never noticed in the cacophony of all of my other weeds) were probably there in my yard all the time, but since my previous yard was such a disaster I never focused on them. Which is a shame, given how the more flamboyant weeds seem so much more susceptible to selective herbicides.

Having read up a little, my plan is aggressive pre-emergent applications this year (already underway), and the glove approach next year for whatever manages to emerge through my (hopefully) thick turf by then. I really don't know if this is the right way to approach it, since I have never fought it before.

Sorry, to get back to your question, RU is taken in by the leaves, and then "translocated" (delivered) to the root, and then the plant is cooked. If you can manage to apply this stuff only to the leaves of the Poa without touching the surrounding grass, that grass should be fine. But if you applied RU in a way that it sprayed or was spread onto your KBG, or if your particular blend of RU (there are a number of them!) included a chemical that remains active in the soil for any length of time, if the KBG was active at the time of application, it is very likely that it is history. As far as I know, regarding turfgrasses, only an experimental species of bentgrass may be Roundup resistant. KBG, no.

Still it would help to know what RU product, specifically, you applied. You could name the product exactly, or list the active ingredients. If the only active ingredient was glyphosate, that is one thing. If there were other active ingredients (dicambra? fluazifop? others?) that may be another.

Please post anything you learn about this! I'm sure there are others in the same boat...

Best,
Paul

Paul,
Maybe when you slit seeded or core aerated you brought the seeds to the surface. That's what happened to me. I have heavy infestations as well. I've probably pulled several large (5 gallon) buckets worth already. I just get down on my knees with my dandelion puller and get what I can out of there. I know I'll never get it all, and I'm about ready to give up, but I guess my efforts will help some. I plan to use a pre-m this August as I won't be seeding these areas.

Greg

Hi Greg, yes I think that's exactly what happened. Part of me wishes I had done something about it last year at seeding time, but I gather the optimal conditions for KBG germination and establishment are similar to those for Poa Annua, and that this just can't be avoided if the seeds are there. Live and learn....

I used the RU with glyphosphate and applied it using a gallon sprayer. It's a tough weed to control anyway you look at it. After it dies, the area needs to be reseeded but the time to do that is usually the time to apply a Pre M. The fun continues.

If there were no active ingredients other than glyphosate then you are good to go. Seeding KBG now is "risky," or so they say, but assuming you are not talking about many square feet, and also assuming that you have not put down a crabgrass pre-emergent, I say what the heck? The risk is just a few lost bucks and lost minutes.

That said, if you have only small spots (a few inches in diameter), I would expect them to fill if you can keep the weeds out of them (and they should be easy to pull in spots like that. If you have aggressively growing grass, you may fill in a spot as large as a dinner plate in a season, but only if you keep the weeds out of it.

Good luck!
Paul